Departmental Faculty of Medicine and Surgery, UniCamillus-Saint Camillus International University of Health and Medical Sciences, Via di Sant'Alessandro 8, 00131 Rome, Italy.
Neurotrauma and Ophthalmology Research Group, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Int J Mol Sci. 2022 Jul 30;23(15):8460. doi: 10.3390/ijms23158460.
In a previous study, we found that administration of ILB, a new low molecular weight dextran sulphate, significantly improved mitochondrial functions and energy metabolism, as well as decreased oxidative/nitrosative stress, of brain tissue of rats exposed to severe traumatic brain injury (sTBI), induced by the closed-head weight-drop model of diffused TBI. Using aliquots of deproteinized brain tissue of the same animals of this former study, we here determined the concentrations of 24 amino acids of control rats, untreated sTBI rats (sacrificed at 2 and 7 days post-injury) and sTBI rats receiving a subcutaneous ILB administration (at the dose levels of 1, 5 and 15 mg/kg b.w.) 30 min post-impact (sacrificed at 2 and 7 days post-injury). Additionally, in a different set of experiments, new groups of control rats, untreated sTBI rats and ILB-treated rats (administered 30 min after sTBI at the dose levels of 1 or 5 mg/kg b.w.) were studied for their neurocognitive functions (anxiety, locomotor capacities, short- and long-term memory) at 7 days after the induction of sTBI. Compared to untreated sTBI animals, ILB significantly decreased whole brain glutamate (normalizing the glutamate/glutamine ratio), glycine, serine and γ-aminobutyric acid. Furthermore, ILB administration restored arginine metabolism (preventing nitrosative stress), levels of amino acids involved in methylation reactions (methionine, L-cystathionine, S-adenosylhomocysteine), and N-acetylaspartate homeostasis. The macroscopic evidences of the beneficial effects on brain metabolism induced by ILB were the relevant improvement in neurocognitive functions of the group of animals treated with ILB 5 mg/kg b.w., compared to the marked cognitive decline measured in untreated sTBI animals. These results demonstrate that ILB administration 30 min after sTBI prevents glutamate excitotoxicity and normalizes levels of amino acids involved in crucial brain metabolic functions. The ameliorations of amino acid metabolism, mitochondrial functions and energy metabolism in ILB-treated rats exposed to sTBI produced significant improvement in neurocognitive functions, reinforcing the concept that ILB is a new effective therapeutic tool for the treatment of sTBI, worth being tested in the clinical setting.
在之前的研究中，我们发现新型低分子量葡聚糖硫酸酯 ILB 的给药可显著改善暴露于闭合性颅脑损伤（由弥漫性颅脑创伤的头部重量下降模型诱导）的大鼠脑组织的线粒体功能和能量代谢，并降低氧化/硝化应激。使用前一项研究中同一动物的去蛋白脑组织的等分试样，我们在此确定了对照大鼠、未治疗的 sTBI 大鼠（在损伤后 2 天和 7 天处死）和接受皮下 ILB 给药的 sTBI 大鼠（剂量水平为 1、5 和 15mg/kg b.w.）的 24 种氨基酸的浓度在损伤后 30 分钟（在损伤后 2 天和 7 天处死）。此外，在另一组实验中，新的对照大鼠组、未治疗的 sTBI 大鼠组和 ILB 治疗大鼠组（在 sTBI 后 30 分钟以 1 或 5mg/kg b.w.的剂量水平给药）在诱导 sTBI 后 7 天研究了其神经认知功能（焦虑、运动能力、短期和长期记忆）。与未治疗的 sTBI 动物相比，ILB 显著降低了全脑谷氨酸（使谷氨酸/谷氨酰胺比正常化）、甘氨酸、丝氨酸和γ-氨基丁酸。此外，ILB 给药恢复了精氨酸代谢（防止硝化应激）、参与甲基化反应的氨基酸水平（蛋氨酸、L-胱硫醚、S-腺苷同型半胱氨酸）和 N-乙酰天冬氨酸的内稳态。ILB 给药对大脑代谢产生有益影响的宏观证据是，与未治疗的 sTBI 动物测量的明显认知下降相比，用 ILB 5mg/kg b.w.治疗的动物组的神经认知功能显著改善。这些结果表明，sTBI 后 30 分钟给予 ILB 可防止谷氨酸兴奋性毒性并使参与关键大脑代谢功能的氨基酸水平正常化。在暴露于 sTBI 的 ILB 治疗大鼠中，氨基酸代谢、线粒体功能和能量代谢的改善导致神经认知功能显著改善，这强化了 ILB 是治疗 sTBI 的一种新的有效治疗工具的概念，值得在临床环境中进行测试。
